If it's for a flyby, no way. If it's a landing, my opinion is the key to a manned landing mission is the availability of a nuclear interplanetary shuttle that could use the martian atmosphere for aerocapture and wait in martian orbit, while on its way back, it would be using chemical or nuclear rocketry to insert into earth orbit. The martian habitat would be sent previously in an unmamned flight and stay on the martian surface definitively. If methane and oxygen can be made in situ on mars, then only a very light ascend vehicle is necessary to reach the orbiter from the Mars surface and this ascend vehicle should even be send back on the ground to be reused.But a nuclear interplanetary shuttle with aerobraking capabilities is a big project. It's not just a question of money but of having all the engineering capabilities, and experience. We could have have it by now if it wasn't for the ISS.

The risks seem clear. There is a non-negligible chance that whoever goes will not return. Also the possability of long term issues if they do make it back.

What are the possible rewards? Celebrity for those involved, however brief. Very inspirational, and a book & movie would surely follow regardless of the outcome. Is there any scienctific knowledge to be gained (other than **** in zero gravity)? Will there be any lasting benefits?

I'm think this belongs in the unlikely category.1) Unlikely to happen.2) If it happens, unlikely to succeed.3) If it succeeds, unlikely to produce any lasting value.

Way too pessimistic.I say first go faster (go nuclear). 3 months max.Then eat less during the space trip. Maybe it would be worthy of reconsidering decreased metabolic rates like the torper of hibernating animals. A slowed metabolism along with a quicker trip should protect against decalcification and muscular atrophy as well.It seemed indeed silly to bring lots of food and water to sustain the intensive weight lifting and bike riding during the trip in space. That's lots of hamburgers to fight bones and muscle loss. And then nothing much is left to eat when they arrive in destination.Radiations: all sci fi movies show small antiradiation shelters. The entire ship doesn't have to be super protected. The water tanks can make a torus around the shelter etc...Also, before departure, astronauts can have their bone marrow and blood frozen for further use in case of cancer.Actually, with a physician onboard and their own frozen blood available, a blood transfusion is possible during the trip.

Notice also that the martian hab has been send months before, it contains food and supply for extra security.

Anyways, the intellectual ressources of the engineers seem unlimited. They can resolve any problems. This way or any other ways. It's just political.

A further caveat to this "only a flyby" aspect of the mission is that apparently the optimal timing and path for minimizing the voyage's duration and fuel requirements will require that closest approach occur at an angle where the majority of the planet will present its "night-side" face to the passing craft. To me, this is analogous to trying to fit a marathon car road trip from the east coast to the Grand Canyon and back in a long weeked, and only arriving right as it's getting dark and having to leave before sunrise in order to make it back in time for work Monday morning. The destination might otherwise be abundantly worth the expense, time, and effort required, but under the circumstances hardly worthwhile simply to be able to say "we've been there".

Yes, lots of problems. They thought a Heavy launcher was the key, but nuclear propulsion(s) seems at least as important and has to come back.

Actually, medium size launchers could be used to assemble a nuclear space ship with a few lauch. Isn't ArianeV heavy capable of ~30 tons in LEO? Three launches make almost for a 100 t, that's not too bad

One must remember that the first manned trips to the moon were flybys as well...

One must also remember that the first manned trip to the Moon, including twenty orbits of that body, took less than a week. The Apollo 11 mission took only eight days. A flyby around Mars would take...how long?

While I recognize that our technology to guide and perhaps propel spacecraft has improved over the years, a human's ability to endure prolonged missions has not. We'd be the weak link in such an endeavor and the most likely to break.

The bottom line, I think, is that it's a whole lot easier to imagine sending someone to Mars than it would be to actually do it. A whole lot cheaper, too. Perhaps we should be content to know that we alone can fashion ever more sophisticated robots to do the dirty work.